A wide variety of mechanical heart valves have been developed for the replacement of defective natural valves. Artificial valves are essentially check valves that operate hemodynamically and in conjunction with the pumping action of the heart. These valves commonly have a valve body of generally hollow cylindrical shape which is designed to support one, two or three occluders or leaflets that are arranged to alternately open and close in order to permit or halt blood flow through a central passageway therein. To install such prosthetic valves into a location associated with a human heart from which a defective natural valve has been excised, a sewing ring is commonly provided which surrounds the valve body and which includes a generally annular cuff through which the prosthetic valve assembly can be sutured to the surrounding tissue to implant the valve in its desired location. Examples of such sewing rings are shown in U.S. Pat. Nos. 4,535,483, 5,035,709 and 5,104,406.
Conventional sewing rings often are fabricated from tubes or sleeves of cloth made of Dacron.TM. fabric or the like. Such a sleeve is often appropriately tied in place by cords or held in place by a plurality of rings, frequently in conjunction with a metal stiffening ring that will be shrink-fit onto the exterior of the valve body when a pyrocarbon valve body is employed. The tubular cloth sleeve is then often rolled upon itself, and its ends may be individually secured or stitched in some way to each other to complete the assembly. Often a foam material ring is incorporated within the rolled tube to serve as a filler that can be easily penetrated by suturing needles.
Just as improvements continue to be sought in the design of occluder constructions for prosthetic heart valves, improvements are likewise sought for heart valve sewing rings, including improvements which will simplify the assembly of such sewing rings and thus reduce the production expense.